Back on January 8th I ordered this rifle http://palmettostatearmory.com/index.php/omni-16-22lr-polymer-m4-rifle-omni22.html It came in to my FFL earlier this week and I picked it up today Three weeks from order to delivery is pretty good all things considered. I also ordered a 12" free float quad rail and some Magpul MBUS sights. The lower is marked multi-caliber I am wanting to install the free float quad rail but have some questions. I heard somewhere that the barrel nut on the Chiappa upper should only be tightened down hand tight and that over tightening it can damage the plastic upper. I can't seem to loosen it with just my hands, should I order an armorer's wrench and use that to loosen it, or will that risk damaging the threads on the upper? The flash hider, front sight post and handgaurds came off pretty easily I also noticed that he barrel isn't threaded, but instead uses a set screw to hold the flash hider on. The OD of the end of the barrel measures exactly .500" can I just use a 1/2-28 die to thread it for use with other muzzle brakes? I know if I was going to use a suppressor I would need to take more care to make sure the threads were centered with the bore, but for use normal muzzle brakes will doing it by hand be ok?